4: Fungal Infections of Skin - Bennett Flashcards
tinea =
refers to all noninvasive cutaneous mycoses expect those caused by candida species (candidiasis)
tinea versicolor, tinea nigra palmaris and piedra proliferate only in…
stratum corneum
tinea versicolor
- pityrosporon orbicular
- grows in sebaceous gland-rich areas of skin
- hypo/hyperpigmented macules that fail to tan with sun exposure
- mild itching
- forearms, face, scalp, upper torso, neck, upper extremities
tinea versicolor
tx: antifungal shampoos (selenium disulfide, zinc pyrithione) topical ketoconazole
tinea nigra palmaris
- c. werneckii
- slow spread within stratum corneum in palms/soles
single brownish to black macule on the palms or soles
sharply marginated and non-scaly
tinea nigra palmaris
tx: removal of lesion by scraping, keratolytic agents, itraconazole, terbinafine
hair nodule appears black
piedraia hortai (tropical environments)
hair nodule appears white
trichosporon cutaneum (southern united states)
treatment for piedras
remove infected hairs by cutting or shaving
black also oral terbinafine
white - topical antifungals
pathogenesis of dermatophyte infections
- once skin is colonized, dermatophyte hyphae peentrate into stratum corneum and migrate deep until granular layer is reached
- spread laterally
most prevalent fungal infection
tinea pedis
interdigital tinea pedis
t. rubrum or t. mentagrophytes
- does not spread beyond intertriginous confines
intensely inflammatory with vesicles and bullae in foci or clusters on foot (type A)
vesicular tinea pedis (caused by any dermatophyte)
dull, erythema, dryness, scaling andhyperkeratosis affecting entire plantar skin of both feet in moccasin distribution
chronic papulosquamous
(mocassin) tinea pedis
t. rubrum organism
sabouraud agar findings for dermatophytes
trichophyton rubrum - white cotton, red
trichonphyton mentagrophytes - white cotton, or cream to tan powder
epidermonphyton floccosum - fuzzy, tan, yellow or green
greatest pathogenic potential of noninvasic cutaneous pathogens
cutaneous candidiasis
describe cutaneous candidiasis
- intertriginous areas
- diabetes, antibiotics, corticosteroids, immunosuppressive meds
- occlusion and moisture in intertriginous areas
- colonization from host’s own GI or mucosal sources
beefy red, scalded skin with irregular margin and satellite pustules
cutaneous candidiasis
- burning, stinging, and itching occurs in the intertriginous areas of affected body part
name 4 invasive cutaneous mycoses (infections that begin at point of focus w/i the skin, secondary to trauma or a foreign object might have penetrated the skin)
- chromoblastomycosis
- mycetoma
- sporotrichosis
- mucormycosis
causative agent chromoblastomycosis
fonseca
philaphora
cladosporium
itchy, warty papule, warty sores
may progress to foul smelling plaque, palm size
chromoblastomycosis
mycologic culture and biopsy are confirmatory (brown branching hyphae)
causative organism mycetoma/maduromycosis
allescheria boydii, madurella, phialophora
mycetomas caused by true fungi =
maduromycosis or eumycotic mycetoma
tx with oral antifungals and amputation
caused by bacteria = actinomycotic
tx with bactrim or dapsone
triad of mycetomas
- sinus tracts draining to skin infection
- discharge fluid containing granules that range in color from white, tan, red or black
- nodular tumorous, fibrotic swelling
chancriform
tender, sometimes painful nodule on the finger or hand accompanied by lymphadenopathy
sign sporotrichosis
systemic mucoses essentially all begin in …
lung
5 common systemic mycoses
- coccidioidomycosis
- histoplasmosis
- blastomycosis
- paracoccidioidomycosis
- cryptococcosis
primary pulmonary infection with flu symptoms
also develop erythema multiforme or erythema nodosum
s/s coccidiomycosis
tx w/ ketoconazole, itraconazole, fluconazole, amp B
verrucous papule, nodule or plaque on face, neck or upper torso
man 30-50
endemic to ohio and mississippi river valley
blastomycosis
tx w/ amp b, ketoconazole, KI
south american blastomycosis
paracoccidiodiomycosis
oropharyngeal ulceration
pain, distress secondary to papules, nodues and verrucous plaques
paracoccidiodiomycosis
tx: sulfonamides and amp B, ketoconazole
variety of morphological lesions including abscesses, tumor-like masses, draining sinuses, panniculitis, etc in immunocompromised ppl
cryptocococcosis
tx w/ amp B, oral flucytosine, fluconazole
assoc with bird and bat feces
histoplasmosis
primarily a pulmonary infection with chronic ulcerative lesions of mucosal surface
4 pathological syndromes of aspergillus
allergic bronchopulmonary aspergillosis
aspergilloma mycetoma
chronic necrotizing pulmonary aspergillosis
invasive aspergillosis
